Showing papers by "David Bacon published in 2020"
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University of Cape Town1, University of California, Berkeley2, University of Turin3, University of Western Australia4, University of Toronto5, ETH Zurich6, Imperial College London7, University of Barcelona8, University of Oslo9, Peking University10, University of the Western Cape11, Aix-Marseille University12, University of Portsmouth13, Tel Aviv University14, University of Amsterdam15, University of Sydney16, University of Geneva17, University of Hamburg18, University of Ferrara19, Centre national de la recherche scientifique20, Complutense University of Madrid21, Queen Mary University of London22, California Institute of Technology23, University of Padua24, University of Manchester25, Purple Mountain Observatory26, Korea Astronomy and Space Science Institute27, University of KwaZulu-Natal28, The University of Texas Rio Grande Valley29, Curtin University30, University of Queensland31, University of Zurich32, Uppsala University33, King's College London34, University of Bologna35, University of the Basque Country36, Huazhong University of Science and Technology37, University of Melbourne38, Guangzhou University39
TL;DR: The Square Kilometre Array (SKA) is a planned large radio interferometer designed to operate over a wide range of frequencies, and with an order of magnitude greater sensitivity and survey speed than any current radio telescope as mentioned in this paper.
Abstract: The Square Kilometre Array (SKA) is a planned large radio interferometer designed to operate over a wide range of frequencies, and with an order of magnitude greater sensitivity and survey speed than any current radio telescope. The SKA will address many important topics in astronomy, ranging from planet formation to distant galaxies. However, in this work, we consider the perspective of the SKA as a facility for studying physics. We review four areas in which the SKA is expected to make major contributions to our understanding of fundamental physics: cosmic dawn and reionisation; gravity and gravitational radiation; cosmology and dark energy; and dark matter and astroparticle physics. These discussions demonstrate that the SKA will be a spectacular physics machine, which will provide many new breakthroughs and novel insights on matter, energy, and spacetime.
223 citations
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University of Manchester1, Queen Mary University of London2, University of Oxford3, Korea Astronomy and Space Science Institute4, University of the Western Cape5, University of Melbourne6, University College London7, University of Barcelona8, University of Geneva9, Imperial College London10, Chinese Academy of Sciences11, University of Portsmouth12, University of Queensland13, ASTRON14, ETH Zurich15, Uppsala University16, Bielefeld University17, International School for Advanced Studies18, Kanagawa University19, University of Edinburgh20
TL;DR: A detailed overview of the cosmological surveys that we aim to carry out with Phase 1 of the Square Kilometre Array (SKA1) and the science that they will enable can be found in this paper.
Abstract: We present a detailed overview of the cosmological surveys that we aim to carry out with Phase 1 of the Square Kilometre Array (SKA1) and the science that they will enable. We highlight three main surveys: a medium-deep continuum weak lensing and low-redshift spectroscopic HI galaxy survey over 5 000 deg2; a wide and deep continuum galaxy and HI intensity mapping (IM) survey over 20 000 deg2 from $z = 0.35$ to 3; and a deep, high-redshift HI IM survey over 100 deg2 from $z = 3$ to 6. Taken together, these surveys will achieve an array of important scientific goals: measuring the equation of state of dark energy out to $z \sim 3$ with percent-level precision measurements of the cosmic expansion rate; constraining possible deviations from General Relativity on cosmological scales by measuring the growth rate of structure through multiple independent methods; mapping the structure of the Universe on the largest accessible scales, thus constraining fundamental properties such as isotropy, homogeneity, and non-Gaussianity; and measuring the HI density and bias out to $z = 6$ . These surveys will also provide highly complementary clustering and weak lensing measurements that have independent systematic uncertainties to those of optical and near-infrared (NIR) surveys like Euclid, LSST, and WFIRST leading to a multitude of synergies that can improve constraints significantly beyond what optical or radio surveys can achieve on their own. This document, the 2018 Red Book, provides reference technical specifications, cosmological parameter forecasts, and an overview of relevant systematic effects for the three key surveys and will be regularly updated by the Cosmology Science Working Group in the run up to start of operations and the Key Science Programme of SKA1.
209 citations
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University of São Paulo1, Spanish National Research Council2, Fermilab3, Stanford University4, Autonomous University of Madrid5, University of Portsmouth6, University of Wisconsin-Madison7, University of Sussex8, University of Pennsylvania9, Pierre-and-Marie-Curie University10, Institut d'Astrophysique de Paris11, Ludwig Maximilian University of Munich12, Argonne National Laboratory13, University College London14, University of Illinois at Urbana–Champaign15, University of Chicago16, University of Michigan17, Ohio State University18, University of Queensland19, Indian Institute of Technology, Hyderabad20, Carnegie Mellon University21, California Institute of Technology22, University of Arizona23, University of California, Santa Cruz24, University of Oslo25, University of Cambridge26, ETH Zurich27, Max Planck Society28, Harvard University29, Lowell Observatory30, Macquarie University31, Princeton University32, Carnegie Institution for Science33, Australian National University34, Texas A&M University35, University of Trieste36, Duke University37, Brookhaven National Laboratory38, Austin Peay State University39, University of Southampton40, Oak Ridge National Laboratory41, Stony Brook University42, University of Edinburgh43
TL;DR: In this paper, a joint analysis of the counts and weak lensing signal of redMaPPer clusters selected from the DES Year 1 dataset was performed using the same shear and source photometric redshifts estimates as were used in the DES combined probes analysis.
Abstract: We perform a joint analysis of the counts and weak lensing signal of redMaPPer clusters selected from the Dark Energy Survey (DES) Year 1 dataset. Our analysis uses the same shear and source photometric redshifts estimates as were used in the DES combined probes analysis. Our analysis results in surprisingly low values for S-8 = sigma(8)(Omega(m)/0.3)(0.5) = 0.65 0.04, driven by a low matter density parameter, Omega(m) = 0.179(-0.038)(+0.031), with sigma(8) - Omega(m) posteriors in 2.4 sigma tension with the DES Y1 3x2pt results, and in 5.6 sigma with the Planck CMB analysis. These results include the impact of post-unblinding changes to the analysis, which did not improve the level of consistency with other data sets compared to the results obtained at the unblinding. The fact that multiple cosmological probes (supernovae, baryon acoustic oscillations, cosmic shear, galaxy clustering and CMB anisotropies), and other galaxy cluster analyses all favor significantly higher matter densities suggests the presence of systematic errors in the data or an incomplete modeling of the relevant physics. Cross checks with x-ray and microwave data, as well as independent constraints on the observable -mass relation from Sunyaev-Zeldovich selected clusters, suggest that the discrepancy resides in our modeling of the weak lensing signal rather than the cluster abundance. Repeating our analysis using a higher richness threshold (lambda >= 30) significantly reduces the tension with other probes, and points to one or more richness -dependent effects not captured by our model.
169 citations
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TL;DR: In this article, the authors used an extensive suite of tailored image simulations to characterize the performance of the shear estimation pipeline applied to the Dark Energy Survey (DES) Year 3 dataset, and provided corrected effective redshift distributions that incorporate statistical and systematic uncertainties, ready for use in DES Year 3 weak lensing analyses.
Abstract: As the statistical power of galaxy weak lensing reaches percent level precision, large, realistic and robust simulations are required to calibrate observational systematics, especially given the increased importance of object blending as survey depths increase. To capture the coupled effects of blending in both shear and photometric redshift calibration, we define the effective redshift distribution for lensing, $n_{\gamma}(z)$, and describe how to estimate it using image simulations. We use an extensive suite of tailored image simulations to characterize the performance of the shear estimation pipeline applied to the Dark Energy Survey (DES) Year 3 dataset. We describe the multi-band, multi-epoch simulations, and demonstrate their high level of realism through comparisons to the real DES data. We isolate the effects that generate shear calibration biases by running variations on our fiducial simulation, and find that blending-related effects are the dominant contribution to the mean multiplicative bias of approximately $-2\%$. By generating simulations with input shear signals that vary with redshift, we calibrate biases in our estimation of the effective redshfit distribution, and demonstrate the importance of this approach when blending is present. We provide corrected effective redshift distributions that incorporate statistical and systematic uncertainties, ready for use in DES Year 3 weak lensing analyses.
54 citations
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TL;DR: In this article, a catalog of 4195 optically confirmed Sunyaev-Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio > 4 in 13,211 deg$^2$ of sky surveyed by the Atacama Cosmology Telescope (ACT).
Abstract: We present a catalog of 4195 optically confirmed Sunyaev-Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise > 4 in 13,211 deg$^2$ of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multi-frequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008-2018, and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ-signal vs. mass scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M500c > 3.8 x 10$^{14}$ MSun, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio > 5 in maps filtered at an angular scale of 2.4'. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ-signal mass-scaling relation, such as the Dark Energy Survey (4566 deg$^2$), the Hyper Suprime-Cam Subaru Strategic Program (469 deg$^2$), and the Kilo Degree Survey (825 deg$^2$). We highlight some noteworthy objects in the sample, including potentially projected systems; clusters with strong lensing features; clusters with active central galaxies or star formation; and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses, and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr.
47 citations
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TL;DR: In this paper, a targeted search specifically looking for subthreshold lensed images of known binary black hole (BBH) observations from GWTC-1 was conducted and the results showed no evidence for additional BBH events.
Abstract: Strong gravitational lensing can produce multiple images of the same gravitational-wave signal, each arriving at different times and with different magnification. Previous work has explored if lensed pairs exist among the known high-significance events from the LIGO and Virgo Collaboration's GWTC-1 catalog and found no evidence of this. However, the possibility remains that weaker counterparts of these events are present in the data, unrecovered by previous searches. We conduct a targeted search specifically looking for subthreshold lensed images of known binary black hole (BBH) observations from GWTC-1. We recover candidates matching three of the additional events first reported by Venumadhav et al. [Phys. Rev. D 101, 083030 (2020)] but find no evidence for additional BBH events. We also find no evidence that any of the Venumadhav et al. observations are lensed counterparts. We demonstrate how this type of counterpart search can constrain hypotheses about the overall source and lens populations and we rule out at very high confidence the extreme hypothesis that all heavy BBH detections are in fact lensed systems at high redshift with intrinsic masses $l15\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$.
36 citations
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IFAE1, University of Chicago2, University of Cambridge3, University of Pennsylvania4, Institute of Cosmology and Gravitation, University of Portsmouth5, Spanish National Research Council6, Stanford University7, University of Oslo8, SLAC National Accelerator Laboratory9, University of Manchester10, University College London11, Ohio State University12, University of Arizona13, Fermilab14, Autonomous University of Madrid15, National Center for Supercomputing Applications16, University of Illinois at Urbana–Champaign17, University of Wisconsin-Madison18, Indian Institute of Technology, Hyderabad19, California Institute of Technology20, Santa Cruz Institute for Particle Physics21, University of Michigan22, Macquarie University23, Lowell Observatory24, University of São Paulo25, Texas A&M University26, Princeton University27, Catalan Institution for Research and Advanced Studies28, University of Southampton29, Brandeis University30, Oak Ridge National Laboratory31, Duke University32, University of Edinburgh33
TL;DR: The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766 and AST-1536171 as mentioned in this paper, and the DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEVER-2016 -0588 and MDM-2015-0509, some of which include ERDF
Abstract: Funding for the DES Projects has been provided by the U.S.
Department of Energy, the U.S. National Science Foundation, the
Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education
Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign,
the Kavli Institute of Cosmological Physics at the University of
Chicago, the Center for Cosmology and Astro-Particle Physics at the
Ohio State University, the Mitchell Institute for Fundamental Physics
and Astronomy at Texas A&M University, Financiadora de Estudos
e Projetos, Fundac¸ao Carlos Chagas Filho de Amparo ˜ a Pesquisa do `
Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento
Cient´ifico e Tecnologico and the Minist ´ erio da Ci ´ encia, Tecnologia ˆ
e Inovac¸ao, the Deutsche Forschungsgemeinschaft and the Collabo- ˜
rating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory,
the University of California, Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y ´
Tecnologicas-Madrid, the University of Chicago, University College ´
London, the DES-Brazil Consortium, the University of Edinburgh,
the Eidgenossische Technische Hochschule (ETH) Z ¨ urich, Fermi ¨
National Accelerator Laboratory, the University of Illinois at UrbanaChampaign, the Institut de Ciencies de l’Espai (IEEC/CSIC), the `
Institut de F´isica d’Altes Energies, Lawrence Berkeley National
Laboratory, the Ludwig-Maximilians Universitat M¨ unchen, and the ¨
associated Excellence Cluster Universe, the University of Michigan,
the National Optical Astronomy Observatory, the University of
Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator
Laboratory, Stanford University, the University of Sussex, Texas
A&M University, and the OzDES Membership Consortium.
Based in part on observations at Cerro Tololo Inter-American
Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy
(AURA) under a cooperative agreement with the National Science
Foundation.
The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766
and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-
71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV2016-0597, and MDM-2015-0509, some of which include ERDF
funds from the European Union. IFAE is partially funded by
the CERCA program of the Generalitat de Catalunya. Research
leading to these results has received funding from the European Research Council under the European Union 7th Framework Program
(FP7/2007-2013) including ERC grant agreements 240672, 291329,
and 306478. We acknowledge support from the Brazilian Instituto
Nacional de Ciencia e Tecnologia (INCT) e-Universe (CNPq grant ˆ
465376/2014-2).
This manuscript has been authored by Fermi Research Alliance,
LLC under Contract No. DE-AC02-07CH11359 with the U.S.
Department of Energy, Office of Science, Office of High Energy
Physics.
32 citations
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TL;DR: In this paper, the authors propagate luminosity function measurements from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) to the quasar (QSO) sample, and derive constraints on relativistic corrections to its power spectrum multipoles.
Abstract: Relativistic effects in clustering observations have been shown to introduce scale-dependent corrections to the galaxy over-density field on large scales, which may hamper the detection of primordial non-Gaussianity $f_\textrm{NL}$ through the scale-dependent halo bias The amplitude of relativistic corrections depends not only on the cosmological background expansion, but also on the redshift evolution and sensitivity to the luminosity threshold of the tracer population being examined, as parametrised by the evolution bias $b_\textrm{e}$ and magnification bias $s$ In this work, we propagate luminosity function measurements from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) to $b_\textrm{e}$ and $s$ for the quasar (QSO) sample, and thereby derive constraints on relativistic corrections to its power spectrum multipoles Although one could mitigate the impact on the $f_\textrm{NL}$ signature by adjusting the redshift range or the luminosity threshold of the tracer sample being considered, we suggest that, for future surveys probing large cosmic volumes, relativistic corrections should be forward modelled from the tracer luminosity function including its uncertainties This will be important to quasar clustering measurements on scales $k \sim 10^{-3} h \, \textrm{Mpc}^{-1}$ in upcoming surveys such as the Dark Energy Spectroscopic Instrument (DESI), where relativistic corrections can overwhelm the expected $f_\textrm{NL}$ signature at low redshifts $z \lesssim 1$ and become comparable to $f_\textrm{NL} \simeq 1$ in the power spectrum quadrupole at redshifts $z \gtrsim 25$
25 citations
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TL;DR: The authors measured the projected number density profiles of galaxies and the splashback feature in clusters selected by the Sunyaev-Zeldovich (SZ) effect from the Advanced Atacama Cosmology Telescope (AdvACT) survey using galaxies monitored by the DES.
Abstract: We measure the projected number density profiles of galaxies and the
splashback feature in clusters selected by the Sunyaev--Zeldovich (SZ) effect
from the Advanced Atacama Cosmology Telescope (AdvACT) survey using galaxies
observed by the Dark Energy Survey (DES). The splashback radius for the
complete galaxy sample is consistent with theoretical measurements from
CDM-only simulations, and is located at $2.4^{+0.3}_{-0.4}$ Mpc $h^{-1}$. We
split the sample based on galaxy color and find significant differences in the
profile shapes. Red galaxies and those in the green valley show a
splashback-like minimum in their slope profile consistent with theoretical
predictions, while the bluest galaxies show a weak feature that appears at a
smaller radius. We develop a mapping of galaxies to subhalos in $N$-body
simulations by splitting subhalos based on infall time onto the cluster halos.
We find that the location of the steepest slope and differences in the shapes
of the profiles can be mapped to differences in the average time of infall of
galaxies of different colors. The minima of the slope in the galaxy profiles
trace a discontinuity in the phase space of dark matter halos. By relating
spatial profiles to infall time for galaxies of different colours, we can use
splashback as a clock to understand galaxy quenching. We find that red galaxies
have on average been in their clusters for over $3.2 ~\rm Gyrs$, green galaxies
about $2.2 ~\rm Gyrs$, while blue galaxies have been accreted most recently and
have not reached apocenter. Using the information from the complete radial
profiles, we fit a simple quenching model and find that the onset of galaxy
quenching in clusters occurs after a delay of about a gigayear, and that
galaxies quench rapidly thereafter with an exponential timescale of $0.6$ Gyr.
23 citations
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University of Manchester1, University of Southampton2, University of Pretoria3, Durham University4, European Southern Observatory5, University of Edinburgh6, University of the Western Cape7, University of Oxford8, INAF9, University of Central Lancashire10, Institute of Cosmology and Gravitation, University of Portsmouth11, Dalhousie University12, University of Hertfordshire13, Shanghai Astronomical Observatory14, Chinese Academy of Sciences15, Leiden University16, Valparaiso University17, Aix-Marseille University18, École Polytechnique Fédérale de Lausanne19, Chalmers University of Technology20, Kapteyn Astronomical Institute21, National Radio Astronomy Observatory22, Rutherford Appleton Laboratory23, Spanish National Research Council24, University of Sussex25, Open University26, Academia Sinica Institute of Astronomy and Astrophysics27
TL;DR: The e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1) as discussed by the authors is a large program of high-resolution 1.5 GHz radio observations of the GOODS-N field comprising similar to 140 h of observations with enhanced-multi-element Remotely Linked Interferometer Network and similar to 40 h with the Very Large Array (VLA).
Abstract: We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising similar to 140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and similar to 40 h with the Very Large Array (VLA). We combine the long baselines of e-MERLIN (providing high angular resolution) with the relatively closely packed antennas of the VLA (providing excellent surface brightness sensitivity) to produce a deep 1.5-GHz radio survey with the sensitivity (similar to 1.5 mu Jy beam(-1)), angular resolution (0.2-0.7 arcsec) and field-of-view (similar to 15x15 arcmin(2)) to detect and spatially resolve star-forming galaxies and active galactic nucleus (AGN) at z greater than or similar to 1. The goal of e-MERGE is to provide new constraints on the deep, sub-arcsecond radio sky which will be surveyed by SKA1-mid. In this initial publication, we discuss our data analysis techniques, including steps taken to model in-beam source variability over an similar to 20-yr baseline and the development of newpoint spread function/primary beam models to seamlessly merge e-MERLIN and VLA data in the uv plane. We present early science results, including measurements of the luminosities and/or linear sizes of similar to 500 galaxies selected at 1.5 GHz. In combination with deep Hubble Space Telescope observations, we measure a mean radio-to-optical size ratio of r(e-MERGE)/r(HST) similar to 1.02 +/- 0.03, suggesting that in most high-redshift galaxies, the similar to GHz continuum emission traces the stellar light seen in optical imaging. This is the first in a series of papers that will explore the similar to kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e-MERGE DR1.
23 citations
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Santa Cruz Institute for Particle Physics1, Fermilab2, California Institute of Technology3, University of Chicago4, University of Pennsylvania5, University of Sussex6, Brookhaven National Laboratory7, Stanford University8, Ohio State University9, University of Geneva10, Argonne National Laboratory11, University of Wisconsin-Madison12, University of Cambridge13, Institut d'Astrophysique de Paris14, Institute of Cosmology and Gravitation, University of Portsmouth15, University College London16, University of Michigan17, Indian Institute of Technology, Hyderabad18, University of Oslo19, Autonomous University of Madrid20, University of Queensland21, Smithsonian Institution22, University of Arizona23, Texas A&M University24, Princeton University25, University of Southampton26, Oak Ridge National Laboratory27, National Center for Supercomputing Applications28, Duke University29
TL;DR: Balrog as mentioned in this paper is a calibration and diagnostic framework used to directly sample the selection and photometric biases of the Dark Energy Survey (DES) Year 3 (Y3) dataset, which is used as a powerful diagnostic and calibration tool for a variety of DES Y3 science, particularly for the calibration of the photometric redshifts of distant "source" galaxies and magnification biases of nearer "lens" galaxies.
Abstract: We describe an updated calibration and diagnostic framework, Balrog, used to directly sample the selection and photometric biases of Dark Energy Survey's (DES) Year 3 (Y3) dataset. We systematically inject onto the single-epoch images of a random 20% subset of the DES footprint an ensemble of nearly 30 million realistic galaxy models derived from DES Deep Field observations. These augmented images are analyzed in parallel with the original data to automatically inherit measurement systematics that are often too difficult to capture with traditional generative models. The resulting object catalog is a Monte Carlo sampling of the DES transfer function and is used as a powerful diagnostic and calibration tool for a variety of DES Y3 science, particularly for the calibration of the photometric redshifts of distant "source" galaxies and magnification biases of nearer "lens" galaxies. The recovered Balrog injections are shown to closely match the photometric property distributions of the Y3 GOLD catalog, particularly in color, and capture the number density fluctuations from observing conditions of the real data within 1% for a typical galaxy sample. We find that Y3 colors are extremely well calibrated, typically within ~1-8 millimagnitudes, but for a small subset of objects we detect significant magnitude biases correlated with large overestimates of the injected object size due to proximity effects and blending. We discuss approaches to extend the current methodology to capture more aspects of the transfer function and reach full coverage of the survey footprint for future analyses.
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TL;DR: In this article, the angular two-point correlation of the LoTSS-DR1 catalogues is compared to the expected cosmological model of a statistically isotropic and homogeneous universe.
Abstract: Context. The LOFAR Two-metre Sky Survey (LoTSS) will eventually map the complete Northern sky and provide an excellent opportunity to study the distribution and evolution of the large-scale structure of the Universe.
Aims. We test the quality of LoTSS observations through a statistical comparison of the LoTSS first data release (DR1) catalogues to expectations from the established cosmological model of a statistically isotropic and homogeneous Universe.
Methods. We study the point-source completeness and define several quality cuts, in order to determine the count-in-cell statistics and differential source count statistics, and measure the angular two-point correlation function. We use the photometric redshift estimates, which are available for about half of the LoTSS-DR1 radio sources, to compare the clustering throughout the history of the Universe.
Results. For the masked LoTSS-DR1 value-added source catalogue, we find a point-source completeness of 99% above flux densities of 0.8 mJy. The counts-in-cell statistic reveals that the distribution of radio sources cannot be described by a spatial Poisson process. Instead, a good fit is provided by a compound Poisson distribution. The differential source counts are in good agreement with previous findings in deep fields at low radio frequencies and with simulated catalogues from the SKA Design Study and the Tiered Radio Extragalactic Continuum Simulation. Restricting the value added source catalogue to low-noise regions and applying a flux density threshold of 2 mJy provides our most reliable estimate of the angular two-point correlation. Based on the distribution of photometric redshifts and the Planck 2018 best-fit cosmological model, the theoretically predicted angular two-point correlation between 0.1 deg and 6 deg agrees reasonably well with the measured clustering for the sub-sample of radio sources with redshift information.
Conclusions. The deviation from a Poissonian distribution might be a consequence of the multi-component nature of a large number of resolved radio sources and/or of uncertainties on the flux density calibration. The angular two-point correlation function is 1 deg and up to the largest scales probed. At a 2 mJy flux density threshold and at a pivot angle of 1 deg, we find a clustering amplitude of A = (5.1 ± 0.6) × 10−3 with a slope parameter of γ = 0.74 ± 0.16. For smaller flux density thresholds, systematic issues are identified, which are most likely related to the flux density calibration of the individual pointings. We conclude that we find agreement with the expectation of large-scale statistical isotropy of the radio sky at the per cent level. The angular two-point correlation agrees well with the expectation of the cosmological standard model.
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University of Portsmouth1, University of Chicago2, Princeton University3, University of Arizona4, Max Planck Society5, Ludwig Maximilian University of Munich6, University College London7, IFAE8, Spanish National Research Council9, Stanford University10, ETH Zurich11, Carnegie Mellon University12, Brookhaven National Laboratory13, Duke University14, University of Edinburgh15, Fermilab16, Institut d'Astrophysique de Paris17, Pierre-and-Marie-Curie University18, University of Manchester19, University of Illinois at Urbana–Champaign20, Indian Institute of Technology, Hyderabad21, University of Michigan22, Autonomous University of Madrid23, University of California, Santa Cruz24, Ohio State University25, Harvard University26, University of Pennsylvania27, Macquarie University28, University of São Paulo29, Texas A&M University30, University of Southampton31, State University of Campinas32, Oak Ridge National Laboratory33, Argonne National Laboratory34
TL;DR: The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766 and AST-1536171, some of which include ERDF funds from the European Union.
Abstract: The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766
and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-
71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV 2016-0597, and MDM-2015-0509, some of which include ERDF
funds from the European Union. IFAE is partially funded by the
CERCA program of the Generalitat de Catalunya. Research leading
to these results has received funding from the European Research
Council under the European Union’s Seventh Framework Program
(FP7/2007-2013) including ERC grant agreements 240672, 291329,
and 306478. We acknowledge support from the Brazilian Instituto
Nacional de Ciencia e Tecnologia (INCT) e-Universe (CNPq grant ˆ
465376/2014-2).
This manuscript has been authored by Fermi Research Alliance,
LLC under Contract No. DE-AC02-07CH11359 with the U.S.
Department of Energy, Office of Science, Office of High Energy
Physics. The United States Government retains and the publisher, by
accepting the article for publication, acknowledges that the United
States Government retains a non-exclusive, paid-up, irrevocable,
world-wide license to publish or reproduce the published form
of this manuscript, or allow others to do so, for United States
Government purposes.
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TL;DR: In this article, a search for RR Lyrae stars using the full six-year data set from the Dark Energy Survey (DES) covering ~5,000 sq. deg.
Abstract: We present a search for RR Lyrae stars using the full six-year data set from the Dark Energy Survey (DES) covering ~5,000 sq. deg. of the southern sky. Using a multi-stage multi-variate classification and light curve template-fitting scheme, we identify RR Lyrae candidates with a median of 35 observations per candidate. We detect 6,971 RR Lyrae candidates out to ~335 kpc, and we estimate that our sample is >70% complete at ~150 kpc. We find excellent agreement with other wide-area RR Lyrae catalogs and RR Lyrae studies targeting the Magellanic Clouds and other Milky Way satellite galaxies. We fit the smooth stellar halo density profile using a broken-power-law model with fixed halo flattening (q = 0.7), and we find strong evidence for a break at $R_0 = 32.1^{+1.1}_{-0.9}$ kpc with an inner slope of $n_1 = -2.54^{+0.09}_{-0.09}$ and an outer slope of $n_2 = -5.42^{+0.13}_{-0.14}$. We use our catalog to perform a search for Milky Way satellite galaxies with large sizes and low luminosities. Using a set of simulated satellite galaxies, we find that our RR Lyrae-based search is more sensitive than those using resolved stellar populations in the regime of large ($r_h > 500$ pc), low-surface-brightness dwarf galaxies. A blind search for large, diffuse satellites yields three candidate substructures. The first can be confidently associated with the dwarf galaxy Eridanus II. The second has a similar distance and proper motion to the ultra-faint dwarf galaxy Tucana II but is separated by ~5 deg. The third is close in projection to the globular cluster NGC 1851 but is ~10 kpc more distant and appears to differ in proper motion.
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TL;DR: In this article, the authors present the calibration of the Dark Energy Survey Year 3 (DES Y3) weak lensing source galaxy redshift distributions from clustering measurements, which can be incorporated into schemes for generating samples of $n(z)$ subject to combined clustering and photometric constraints.
Abstract: We present the calibration of the Dark Energy Survey Year 3 (DES Y3) weak lensing source galaxy redshift distributions $n(z)$ from clustering measurements. In particular, we cross-correlate the weak lensing (WL) source galaxies sample with redMaGiC galaxies (luminous red galaxies with secure photometric redshifts) and a spectroscopic sample from BOSS/eBOSS to estimate the redshift distribution of the DES sources sample. Two distinct methods for using the clustering statistics are described. The first uses the clustering information independently to estimate the mean redshift of the source galaxies within a redshift window, as done in the DES Y1 analysis. The second method establishes a likelihood of the clustering data as a function of $n(z)$, which can be incorporated into schemes for generating samples of $n(z)$ subject to combined clustering and photometric constraints. Both methods incorporate marginalisation over various astrophysical systematics, including magnification and redshift-dependent galaxy-matter bias. We characterise the uncertainties of the methods in simulations; the first method recovers the mean $z$ of tomographic bins to RMS (precision) of $\sim 0.014$. Use of the second method is shown to vastly improve the accuracy of the shape of $n(z)$ derived from photometric data. The two methods are then applied to the DES Y3 data.
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TL;DR: In this article, a framework and an open-source python toolkit are presented to analyse the 2-point statistics of 3D fluctuations in the context of HI intensity maps using the multipole expansion formalism.
Abstract: We present a framework and an open-source python toolkit to analyse the 2-point statistics of 3D fluctuations in the context of HI intensity maps using the multipole expansion formalism. We include simulations of the cosmological HI signal using N-body and log-normal methods, foregrounds and their removal, as well as instrumental effects. Using these simulations and analytical modelling, we investigate the impact of foreground cleaning and the instrumental beam on the power spectrum multipoles as well as on the Fourier space clustering wedges. We find that both the instrumental beam and the foreground removal can produce a quadrupole (and a hexadecapole) signal, and demonstrate the importance of controlling and accurately modelling these effects for precision radio cosmology. We conclude that these effects can be modelled with reasonable accuracy using our multipole expansion technique. We also perform an MCMC analysis to showcase the effect of foreground cleaning on the estimation of the HI abundance and bias parameters. The accompanying python toolkit is available at this https URL, and includes an interactive suite of examples to aid new users.
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TL;DR: In this paper, the viability of exploiting lensing time delays to observe strongly gravitationally lensed supernovae (gLSNe) from first light was determined, and the possibility of performing early-time observations for Type IIP and Type Ia SNe in LSST-discovered systems was explored.
Abstract: We determine the viability of exploiting lensing time delays to observe strongly gravitationally lensed supernovae (gLSNe) from first light. Assuming a plausible discovery strategy, the Legacy Survey of Space and Time (LSST) and the Zwicky Transient Facility (ZTF) will discover ∼110 and ∼1 systems per year before the supernova (SN) explosion in the final image, respectively. Systems will be identified 11.7^(+29.8)_(−9.3) d before the final explosion. We then explore the possibility of performing early-time observations for Type IIP and Type Ia SNe in LSST-discovered systems. Using a simulated Type IIP explosion, we predict that the shock breakout in one trailing image per year will peak at ≲24.1 mag (≲23.3) in the B-band (F218W), however evolving over a time-scale of ∼30 min. Using an analytic model of Type Ia companion interaction, we find that in the B-band we should observe at least one shock cooling emission event per year that peaks at ≲26.3 mag (≲29.6) assuming all Type Ia gLSNe have a 1 M_⊙ red giant (main sequence) companion. We perform Bayesian analysis to investigate how well deep observations with 1 h exposures on the European Extremely Large Telescope would discriminate between Type Ia progenitor populations. We find that if all Type Ia SNe evolved from the double-degenerate channel, then observations of the lack of early blue flux in 10 (50) trailing images would rule out more than 27 per cent (19 per cent) of the population having 1 M_⊙ main sequence companions at 95 per cent confidence.
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University of Queensland1, Ohio State University2, University of Pennsylvania3, INAF4, Swinburne University of Technology5, University of Sydney6, Australian National University7, Duke University8, University of Southampton9, University of São Paulo10, Fermilab11, Institut d'Astrophysique de Paris12, University of Sussex13, University College London14, Stanford University15, SLAC National Accelerator Laboratory16, National Center for Supercomputing Applications17, University of Illinois at Urbana–Champaign18, IFAE19, Spanish National Research Council20, Indian Institute of Technology, Hyderabad21, Santa Cruz Institute for Particle Physics22, Autonomous University of Madrid23, University of Michigan24, Smithsonian Institution25, Macquarie University26, Lowell Observatory27, Texas A&M University28, Princeton University29, Catalan Institution for Research and Advanced Studies30, University of Chicago31, Brandeis University32, Oak Ridge National Laboratory33, Max Planck Society34
TL;DR: In this paper, the effects of weak gravitational lensing on observations of 196 spectroscopically confirmed Type Ia supernovae (SNe Ia) from years 1 to 3 of the Dark Energy Survey (DES).
Abstract: We consider the effects of weak gravitational lensing on observations of 196 spectroscopically confirmed Type Ia Supernovae (SNe Ia) from years 1 to 3 of the Dark Energy Survey (DES).We simultaneously measure both the angular correlation function and the non-Gaussian skewness caused by weak lensing. This approach has the advantage of being insensitive to the intrinsic dispersion of SNe Ia magnitudes. We model the amplitude of both effects as a function of σ8, and find σ8 =1.2+0.9-0.8. We also apply our method to a subsample of 488 SNe from the Joint Light-curve Analysis (JLA; chosen to match the redshift range we use for this work), and find σ8 =0.8+1.1-0.7. The comparable uncertainty in σ8 between DES-SN and the larger number of SNe from JLA highlights the benefits of homogeneity of the DES-SN sample, and improvements in the calibration and data analysis.
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TL;DR: In this article, Gaussian process regression (GPR) was used to interpolate the distortion field to arbitrary locations in each exposure, and the results showed that the GPR correction reduced the variance of the turbulent distortions.
Abstract: Stochastic field distortions caused by atmospheric turbulence are a fundamental limitation to the astrometric accuracy of ground-based imaging. This distortion field is measurable at the locations of stars with accurate positions provided by the Gaia DR2 catalog; we develop the use of Gaussian process regression (GPR) to interpolate the distortion field to arbitrary locations in each exposure. We introduce an extension to standard GPR techniques that exploits the knowledge that the 2-dimensional distortion field is curl-free. Applied to several hundred 90-second exposures from the Dark Energy Survey as a testbed, we find that the GPR correction reduces the variance of the turbulent distortions $\approx12\times$, on average, with better performance in denser regions of the Gaia catalog. The RMS per-coordinate distortion in the $riz$ bands is typically $\approx7$ mas before any correction, and $\approx2$ mas after application of the GPR model. The GPR astrometric corrections are validated by the observation that their use reduces, from 10 to 5 mas RMS, the residuals to an orbit fit to $riz$-band observations over 5 years of the $r=18.5$ trans-Neptunian object Eris. We also propose a GPR method, not yet implemented, for simultaneously estimating the turbulence fields and the 5-dimensional stellar solutions in a stack of overlapping exposures, which should yield further turbulence reductions in future deep surveys.
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University of Geneva1, Ohio State University2, Stanford University3, University of Illinois at Urbana–Champaign4, National Center for Supercomputing Applications5, Brookhaven National Laboratory6, University of Oxford7, University of Manchester8, University of Pennsylvania9, Fermilab10, Argonne National Laboratory11, University of Cambridge12, University of Wisconsin-Madison13, SLAC National Accelerator Laboratory14, Texas A&M University15, University of Nottingham16, University of Queensland17, Carnegie Mellon University18, University of Chicago19, Santa Cruz Institute for Particle Physics20, California Institute of Technology21, University of Michigan22, Princeton University23, ETH Zurich24, Duke University25, University of São Paulo26, Institute of Cosmology and Gravitation, University of Portsmouth27, Institut d'Astrophysique de Paris28, University of Sussex29, University College London30, University of La Laguna31, Spanish National Research Council32, IFAE33, INAF34, University of California, Berkeley35, Indian Institute of Technology, Hyderabad36, Ludwig Maximilian University of Munich37, University of Arizona38, University of Oslo39, Autonomous University of Madrid40, Smithsonian Institution41, Macquarie University42, Lowell Observatory43, Radcliffe Institute for Advanced Study44, Catalan Institution for Research and Advanced Studies45, Max Planck Society46, University of Southampton47, Oak Ridge National Laboratory48, University of Edinburgh49
TL;DR: In this paper, the authors present a catalogue for the DES 3-year cosmology analysis of those four fields with full 8-band coverage, totalling $5.88~$ sq. deg after masking.
Abstract: We describe the Dark Energy Survey (DES) Deep Fields, a set of images and associated multi-wavelength catalogue ($ugrizJHKs$) built from Dark Energy Camera (DECam) and Visible and Infrared Survey Telescope for Astronomy (VISTA) data. The DES Deep Fields comprise 11 fields (10 DES supernova fields plus COSMOS), with a total area of $\sim30~$ square degrees in $ugriz$ bands and reaching a maximum $i$-band depth of 26.75 (AB, $10\sigma$, 2"). We present a catalogue for the DES 3-year cosmology analysis of those four fields with full 8-band coverage, totalling $5.88~$ sq. deg. after masking. The catalogue is constructed in order to provide a sample of effectively noiseless galaxies (S/N $>\sqrt{10}\times$ their equivalents in the main DES survey), to be used as a prior on the population of objects observed in the DES and their moments in light distribution, a source of high-quality redshift information in constructing source galaxy redshift distributions for weak lensing analyses, and a host of deep extragalactic science. Numbering $2.8~$million objects ($1.6~$million post masking), our catalogue is drawn from images coadded to consistent depths of $r=25.7, i=25, z=24.3$ mag. We use a new model-fitting code, built upon established methods, to deblend sources and ensure consistent colours across the $u$-band to $Ks$-band wavelength range. We further detail the tight control we maintain over the point-spread function modelling required for the model fitting, astrometry and consistency of photometry between the four fields. The catalogue allows us to perform a careful star-galaxy separation and produces excellent photometric redshift performance (${\rm NMAD} = 0.023$ at $i<23$). The Deep-Fields catalogue will be made available as part of the cosmology data products release, following the completion of the DES 3-year weak lensing and galaxy clustering cosmology work.
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TL;DR: This work trains a GAN to produce both weak lensing convergence maps and dark matter overdensity field data for multiple redshifts, cosmological parameters and modified gravity models, and applies the technique of latent space interpolation to control which outputs the algorithm produces.
Abstract: Generative adversarial networks (GANs) have been recently applied as a novel emulation technique for large scale structure simulations. Recent results show that GANs can be used as a fast, efficient and computationally cheap emulator for producing novel weak lensing convergence maps as well as cosmic web data in 2-D and 3-D. However, like any algorithm, the GAN approach comes with a set of limitations, such as an unstable training procedure and the inherent randomness of the produced outputs. In this work we employ a number of techniques commonly used in the machine learning literature to address the mentioned limitations. In particular, we train a GAN to produce both weak lensing convergence maps and dark matter overdensity field data for multiple redshifts, cosmological parameters and modified gravity models. In addition, we train a GAN using the newest Illustris data to emulate dark matter, gas and internal energy distribution data simultaneously. Finally, we apply the technique of latent space interpolation to control which outputs the algorithm produces. Our results indicate a 1-20% difference between the power spectra of the GAN-produced and the training data samples depending on the dataset used and whether Gaussian smoothing was applied. Finally, recent research on generative models suggests that such algorithms can be treated as mappings from a lower-dimensional input (latent) space to a higher dimensional (data) manifold. We explore such a theoretical description as a tool for better understanding the latent space interpolation procedure.